The long-term objectives are to make correlated studies of facial form and masticatory function in the presence of experimental variables, and to formulate from these studies new concepts for the diagnosis and treatment of severe malocclusion and jaw dysfunction. Alterations of facial growth and masticatory function will be produced experimentally in monkeys by means of mechanical forces and experimental brain lesions. Documentation of changes in form will be cephalometric and histologic; function will be studied by mandibular tracking combined with EMG analysis.